Birds across the Arctic are experiencing increasing stress related to climate change that contributes to foraging and reproductive failures according to Canadian researchers. The reasons for the decline in murres, falcons, ptarmigans, gulls and skuas are not altogether understood, but one reason is perfectly clear: hungry polar bears unable to hunt seals because of declining sea ice are gobbling up hundreds of birds' eggs. A researcher with Environment Canada witnessed a polar bear rampage through 300 eider duck nests each containing four to five eggs. Nearly all of the eggs were consumed in a forty eight hour period. Ground nesting birds are easy targets, but cliff dwellers are not save either. Thick-billed murres are loosing their eggs to bears that walk over the edge and along ledges to raid nests. Polar bears prefer red seal meat, but they must remain land bound until the sea freezes over. Now freeze-over is thirty days late and thaw is thirty days earlier forcing bears to find other food sources. Bear incursions into nesting areas have increased seven times since the 1980s.
Bears are not the only reason for some Arctic bird specie's declines. As many as sixty percent of adult peregrines in the Yukon are not nesting. Collapsing prey cycles may be a reason. Higher Arctic temperatures have an impact on vegetation which in turn affects the rodent populations on which predatory birds depend for food. A team of Danish scientists
recently documented how a lemming collapse at two Greenland sites resulted in a 98% drop in snowy owls. Lemmings are sensitive to snow conditions because it provides insulation for nestlings. Increasing amounts of rain on the west coast of Hudson Bay are is causing up to a third of peregrine chicks to die of hypothermia. Their downy white coats are well adapted for snow cover, but wet down provides little insulation value. Ivory gulls like bears maybe suffering from retreating sea ice which makes it more difficult to fish. Evidence of high mercury levels in seal carcasses which the gulls scavenge could be another factor in their population declines.
The circumpolar Arctic is remote and vast, encompassing multiple international borders, so scientific research there is fragmented. Add to these diplomatic, logistical and funding problems the complexity of the natural relationships involved and it is easy to understand why man is unprepared for the rapid changes taking place. To obtain a clearer picture of what is happening to Arctic wildlife as a result of climate change, international cooperation and more intensive study is needed.